Articulated cartridges for pneumatic conveyance

ABSTRACT

This disclosure includes a method and apparatus for propelling a cartridge through a pneumatic tube by creating a pressure differential within the tube and for braking the cartridge by reversing the pressure differential. Valve means are provided in each end of the cartridge to enable the pressure differential to act on the leading end of the cartridge when propelling the cartridge and to act on the trailing end of the cartridge during braking so that longitudinal compression of the cartridge is precluded.

United States Patent l 13,5s0,s27

Simon Cynobcr Bezons, France 762,253

Sept. 16, 1968 May 25, 1971 Saunier Duval Paris, France Inventor Appl. No. Filed Patented Assignee ARTICULATED CARTRIDGES FOR PNEUMATIC CONVEYANCE 9 Claims, 4 Drawing Figs.

U.S. Cl 243/38, 243/32, 243/39 Int. Cl 865g 51/04 Field of Search 243/32, 1,

[56] References Cited UNTTED STATES PATENTS 165,092 6/1875 Gregg 243/39 381,401 4/1888 Mayall..... 243/39 1,183,198 5/1916 Hills 243/32 3,448,944 6/1969 Shellene 243/32 Primary Examiner-Harvey C. Hornsby Attorney-Kenway, Jenney and Hildreth ABSTRACT: This disclosure includes a method and apparatus for propelling a cartridge through a pneumatic tube by creating a pressure differential within the tube and for braking the cartridge by reversing the pressure differential. Valve means are provided in each end of the cartridge to enable the pressure differential to act on the leading end of the cartridge when propelling the cartridge and to act on the trailing end of the cartridge during braking so that longitudinal compression of the cartridge is precluded.

Patented May 25, 1971 3,580,527

2 Sheets-Sheet 1 ATTORNEYS Patented May 25, 1971 3,580,527

2 Sheets-Sheet 2 v M ///i //i/ Ha I FIG.4

INVENTOR SIMON CYNOBER TTORNEYS ARTICULATED CARTRIDGES FOR PNEUMATIC CONVEYANCE SUMMARY OF THE INVENTION My invention is concerned with an improved method and apparatus for transporting a cartridge through a pneumatic tube by creating a pneumatic pressure differential within the tube to propel the cartridge through the tube and for braking the cartridge by reversing the pressure differential. It is useful particularly in connection with a cartridge that includes a number of cartridge sections flexibly joined in trainlike fashion to enable the cartridge to assume a curved configuration as it is propelled through a curved section of the tube.

In pneumatic tube systems, and particularly systems of relatively large dimensions, it is customary to provide a number of articulated cartridges connected in a train. The end sections of the cartridge are constructed as to effect a continuous seal along the inner wall of the tube. Such a construction results in a flexible unitary cartridge which is movable within tubes having a relatively small radius of curvature. By reason of its flexible nature the assembled unitary cartridge may adopt a variable profile with accentuated bends and may adapt itself readily to the configurations of the tube. This type of cartridge advantageously lends itself to the conveyance of heavy loads such as mail bags. The articulated construction provides a device of wide flexibility in that the cartridge sections readily may be added, removed or interchanged in accordance with the load to be carried or to replace a worn out cartridge section should this be necessary.

Because of the elongate and flexible nature of the unitary cartridge, difficulties frequently are encountered when starting, braking or stopping the cartridge within the tube. Movement of the articulated cartridge through the pneumatic tube is caused by a pressure reduction at the downstream end of the tube or by an increase in pressure at the upstream end of the tube. In other words, in order to move the cartridge through the tube a higher pneumatic pressure is generated within the tube upstream of the cartridge thus pushing the cartridge downstream toward the region of lower pressure. It will be apparent that the driving force which induces this downstream movement is applied therefore at the back, trailing end of the cartridge and. tends to compress and push the cartridge sections together. It will be appreciated that when the cartridge sections are not disposed in a straight line, as when rounding a curve within the tube, the compressive nature of the driving force will tend to deform the cartridge and may sometimes cause the sections to become jammed. This jamming of the cartridge sections results in excessive friction between the cartridge sections and the tube and may cause damage to occur rapidly.

When braking such cartridges the pressure differential is reversed, that is, the pneumatic pressure in the tube downstream of the cartridge is increased to the degree required to brake or stop the downstream movement of the cartridge. The braking force thus is applied normally to the leading end of the cartridge which imposes a similar compressive stress on the articulated cartridge sections.

My invention eliminated the foregoing disadvantages by causing the driving force to be applied to the leading end of the cartridge train when moving the cartridge downstream so that the cartridge will be pulled by the leading end instead of being pushed by the trailing end. Similarly when braking the cartridge, the braking force is applied to the trailing end of the train. Thus the stress imposed on the cartridge sections is tensile in character and insures that the cartridge section will not be pushed and jammed together. In accordance with my invention I provide a check valve at both the leading and trailing ends of the cartridge. Each check valve is effective to communicate the pressure developed on one side of the cartridge to the interior of the cartridge so that the resultant force may act on the other end and interiorly of the cartridge.

My invention will now be described in greater detail with reference to the accompanying drawings wherein:

FIG. 1 is a substantially schematic section of the cartridge train as it is being braked;

FIG. 2 is a substantially schematic section of the cartridge train as it is propelled through the tube;

FIG. 3 is an elevation in section through the end of the section of the cartridge showing one type of check valve in accordance with my invention; and

FIG. 4 is an illustration similar to FIG. 3 showing an alternative type of check valve.

The cartridge 10 includes a pair of end sections 12 and 14, which for convenience, may be of identical construction, and a number of intermediate sections 16 which are connected to each other in trainlike fashion by the flexible articulations shown diagrammatically by the reference character 18. The

end sections l2, l4 commonly include a rigid reinforcing shell V 20 which is provided with an external facing 22. The facing 22 may be made from nylon tissue or similar material which is effective to insure a seal along the inner surface 21 of the tube 23 while facilitating the sliding of the cartridge within the tube 23. An intermediate layer 24 (see FIGS. 3 and 4), usually made of rubber, foam or similar material, is interposed between the reinforcing shell 20 and the outer facing 22 to distribute evenly the load within the tube 23. Each of the and sections 12 and I4 is provided with a valve 26, 28, respectively. As shown more clearly in FIG. 3 the end section 12 has a center orifice 30. Tightening plates (not shown) are placed on the internal and external sides of the reinforcing shell near the orifice 30 and serve to press the linings 22, 24 firmly to the reinforcing shell 20, the inner tightening plate serving as a mount for the valve support 32. A collar 34 is secured to the valve support 32 and receives slidably the valve stem 36 of the valve 26. A compression spring 38 is disposed coaxially about the valve stem 36 and is compressed between the collar 34 and valve 26 to bias the valve 26 against a circular valve seat 40 thus biasing the valve in a closed position. A gasket 42 may be provided between the valve seat 40 and the valve 26 to improve the seal. In accordance with my invention each of the end sections 12, 14 is provided with such a valving arrangement.

An alternative valving arrangement is shown in FIG. 4 in which a flapper valve 42 is engageable with an inwardly extending valve seat 44 which defines the orifice 46 formed in the end section. A gasket 48 may be provided to insure a proper seal. The valve seat 44 is secured to and is supported from the internal tightening plate (not shown) by any conventional means. The flapper valve 42 is pivoted to the internal tightening plate at the fixed pivot 50 and is balanced by the weight 52 which is carried on a radially extending rod 54 secured to the flapper valve 42. The flapper valve 42 is biased in the closed position shown in solid in FIG. 4 by a spiral spring 56 which is attached to the rod 54 at 58 and to the fixed pivot 50. This arrangement provides a balanced assembly which enables fine adjustment of the pressure required to open the valve 42 by varying the position of the weight 52 on the rod 54.

When operating my invention to propel the cartridge 10 downstream, as shown by the arrow 60 in FIG. 2, a pressure differential is generated between the upstream and downstream ends of the cartridge 10. This may be effected by introducing compressed air, as from a pump, into the upstream end of the tube 23, reducing the pressure in the downstream end of the tube or by a combination of both. As the pressure differential (shown schematically by the arrow 62) builds up to set the cartridge 10 in motion downstream the valve 26 opens and an identical pressure differential develops within the cartridge, this pressure differential being applied to the interior of the other, downstream end section 14 as represented schematically by the arrows 64. This causes the valve 28 to be pressed firmly against its associated valve seat 40 and insures that the downstream valve 28 will be closed and sealed. Thus the pressure differential is applied to the downstream, leading end section 14 which in turn pulls the trailing cartridge sections 16 and end section 12 through the tube 23 thus relieving the cartridge 10 of the compressive stress that would be created if the driving force were applied at the trailing end section I2.

FIG. 1 is an illustration of the cartridge 10 during braking or stopping in accordance with my invention. As the cartridge 110 moves downstream the pressure differential is reversed so that the downstream pressure illustrated schematically by the arrow 66 exceeds the upstream pressure. The rise in downstream pressure causes the valve 28 to open thus enabling the reversed pressure differential to be communicated to the trailing end section 12. This closes the valve 26 and enables the braking force shown schematically by the arrows 68 resulting from the reversed pressure differential to act on the trailing end section 12. When braking in this manner the cartridge I is not subjected to the conventional compres sive stresses thus eliminating any tendency of the articulated cartridge sections 16 to become jammed.

It should be noted that when operating within inclined or vertical positions of the tube 23 the cartridge may, under its own weight, reach a higher velocity than that of the air flowing in the pneumatic tube 23. As such a limit velocity is approached, the force acting on the downstream end section 14 and its valve 28 will increase to cause opening of the valve 28 to initiate braking of the cartridge at the trailing section. It should be noted further that the primary function of the springs 38, 56 is to preclude the opening of the valves 26, 42 respectively by virtue of their own weight when disposed at an inclined or vertical attitude. As mentioned earlier, the springs also may be calibrated to regulate the pressure differential required to open the valves. Thus the springs may be adjusted to provide the desired braking characteristics when the cartridge is traveling at higher velocities and particularly when in an inclined attitude.

It will be understood that the foregoing description is intended merely to be illustrative of .my invention and that modification will be apparent to those skilled in the art without departing from its spirit.

I claim:

1. In a system for transporting a cartridge, having a leading end and a trailing end, through a tube by applying a pneumatic pressure differential to the portions of the tube that are upstream and downstream of said cartridge relative to the direction of travel to urge said cartridge downstream and to brake said cartridge by reversing said pressure differential, the improvement comprising:

means enabling said pressure difierential to act directly on the leading end of said cartridge when propelling said cartridge downstream so that said leading end of said cartridge may pull the trailing end of said cartridge downstream; and

means enabling said reversed pressure differential to be applied directly to the trailing end of said cartridge when braking said cartridge to thereby relieve said cartridge of compressive stress resulting from said pressure differentials. I

2. An apparatus as claimed in claim 1 wherein said means enabling said pressure differential to act directly on said leading end of said cartridge comprises:

valve means mounted to said trailing end of said cartridge for communicating the upstream end of said tube with the interior of said cartridge so that when said valve is open said upstream pressure may be communicated to the in terior of said leading end of said cartridge,

said valve means being so constructed and arranged as to permit air to enter into said cartridge but to preclude the flow of air from said cartridge into said tube.

3. An apparatus as claimed in claim 1 wherein said means enabling said pressure differential to act directly on said trailing end of said cartridge comprises:

valve means mounted to said leading end of said cartridge for communicating the downstream end of said tube with the interior of said cartridge so that when said valve is open said downstream pressure may be communicated to the interior ofsaid trailing end of said cartridge,

said valve means being so constructed and arranged as to permit air to enter said cartridge but to preclude the flow of air from said cartridge to said tube.

4. An apparatus as claimed in claim 1 wherein said means enabling said pressure differentials to act alternatively on said leading end trailing ends of the interior of said cartridge com prises:

a valve disposed at each end of said cartridge, each of said valves being so constructed as to permit only unidirectional flow of air-from said tube into said cartridge;

means responsive to an increased pneumatic pressure within said tube and at one end of said cartridge to open the valve at said end of said cartridge thereby increasing the pressure within said cartridge; and

means responsive to said increased pressure within said cartridge to close the other of said valves at said other end of said cartridge whereby said increased pressure will be applied to the other end of and within said cartridge whereby the pressure differential of said upstream and downstream portions of said tube may be applied to said other end of said cartridge.

5. An apparatus as claimed in claim 4 further comprising:

means biasing each of said valves in a normally closed position, said biasing means being effective to permit yieldable opening of each of said valves in response to a predetermined pneumatic pressure generated within said tube.

6. In a cartridge which has a leading end and a trailing end and which is adapted to be propelled through a pneumatic tube in response to application of a pressure differential at the upstream and downstream ends of said tube relative to the direction of travel and to be braked by reversal of said pressure differential the improvement comprising:

valve means mounted to at least one end of said cartridge said valve being so constructed as to communicate that portion of said tube adjacent said end of said cartridge with the interior of said cartridge;

means biasing said valve means in a normally closed position;

means responsive to an increased pressure within said one end of said tube to open said valve means thereby causing said pressure within said one end of said tube to act interi orly of and on the other end of said cartridge whereby the force of said increased pressure may be applied to said other end of said cartridge.

7. In a method for transporting a cartridge, having a leading end and a trailing end, through a tube by applying a pneumatic pressure differential to the upstream and downstream portions of said tube relative to the direction of travel and wherein braking of said cartridge is effected by reversing said pressure differential the improvement comprising:

directing the force created by said pressure differential to the leading downstream end of said cartridge thereby relieving said cartridge of compressive stresses; and

directing the force created by said reversed pressure differential to the trailing upstream end of said cartridge whereby said cartridge may be relieved of compressive stresses during braking.

8. In a method for pneumatically transporting a cartridge, having a leading end and a trailing end, through a tube by applying a pneumatic pressure differential to the upstream and downstream portions of said tube relative to the direction of travel, the improvement comprising:

communicating the air within the upstream end of said tube with the interior of the leading end of said cartridge whereby the transporting force generated by said pressure difierential may be applied to said downstream end of said cartridge.

9. In a method for transporting a cartridge, having a leading end and a trailing end, through a tube by applying a pneumatic pressure differential to the upstream and downstream portions of said tube relative to the direction of travel and wherein braking of said cartridge is effected by reversing said pressure interior of the trailing end of said cartridge whereby the braking force generated by said reversed pressure differential may act on the upstream end of said cartridge. 

1. In a system for transporting a cartridge, having a leading end and a trailing end, through a tube by applying a pneumatic pressure differential to the portions of the tube that are upstream and downstream of said cartridge relative to the direction of travel to urge said cartridge downstream and to brake said cartridge by reversing said pressure differential, the improvement comprising: means enabling said pressure differential to act directLy on the leading end of said cartridge when propelling said cartridge downstream so that said leading end of said cartridge may pull the trailing end of said cartridge downstream; and means enabling said reversed pressure differential to be applied directly to the trailing end of said cartridge when braking said cartridge to thereby relieve said cartridge of compressive stress resulting from said pressure differentials.
 2. An apparatus as claimed in claim 1 wherein said means enabling said pressure differential to act directly on said leading end of said cartridge comprises: valve means mounted to said trailing end of said cartridge for communicating the upstream end of said tube with the interior of said cartridge so that when said valve is open said upstream pressure may be communicated to the interior of said leading end of said cartridge, said valve means being so constructed and arranged as to permit air to enter into said cartridge but to preclude the flow of air from said cartridge into said tube.
 3. An apparatus as claimed in claim 1 wherein said means enabling said pressure differential to act directly on said trailing end of said cartridge comprises: valve means mounted to said leading end of said cartridge for communicating the downstream end of said tube with the interior of said cartridge so that when said valve is open said downstream pressure may be communicated to the interior of said trailing end of said cartridge, said valve means being so constructed and arranged as to permit air to enter said cartridge but to preclude the flow of air from said cartridge to said tube.
 4. An apparatus as claimed in claim 1 wherein said means enabling said pressure differentials to act alternatively on said leading end trailing ends of the interior of said cartridge comprises: a valve disposed at each end of said cartridge, each of said valves being so constructed as to permit only unidirectional flow of air from said tube into said cartridge; means responsive to an increased pneumatic pressure within said tube and at one end of said cartridge to open the valve at said end of said cartridge thereby increasing the pressure within said cartridge; and means responsive to said increased pressure within said cartridge to close the other of said valves at said other end of said cartridge whereby said increased pressure will be applied to the other end of and within said cartridge whereby the pressure differential of said upstream and downstream portions of said tube may be applied to said other end of said cartridge.
 5. An apparatus as claimed in claim 4 further comprising: means biasing each of said valves in a normally closed position, said biasing means being effective to permit yieldable opening of each of said valves in response to a predetermined pneumatic pressure generated within said tube.
 6. In a cartridge which has a leading end and a trailing end and which is adapted to be propelled through a pneumatic tube in response to application of a pressure differential at the upstream and downstream ends of said tube relative to the direction of travel and to be braked by reversal of said pressure differential the improvement comprising: valve means mounted to at least one end of said cartridge said valve being so constructed as to communicate that portion of said tube adjacent said end of said cartridge with the interior of said cartridge; means biasing said valve means in a normally closed position; means responsive to an increased pressure within said one end of said tube to open said valve means thereby causing said pressure within said one end of said tube to act interiorly of and on the other end of said cartridge whereby the force of said increased pressure may be applied to said other end of said cartridge.
 7. In a method for transporting a cartridge, having a leading end and a trailing end, through a tube by applying a pneumatic pressure differential to the upstream and downstream portioNs of said tube relative to the direction of travel and wherein braking of said cartridge is effected by reversing said pressure differential the improvement comprising: directing the force created by said pressure differential to the leading downstream end of said cartridge thereby relieving said cartridge of compressive stresses; and directing the force created by said reversed pressure differential to the trailing upstream end of said cartridge whereby said cartridge may be relieved of compressive stresses during braking.
 8. In a method for pneumatically transporting a cartridge, having a leading end and a trailing end, through a tube by applying a pneumatic pressure differential to the upstream and downstream portions of said tube relative to the direction of travel, the improvement comprising: communicating the air within the upstream end of said tube with the interior of the leading end of said cartridge whereby the transporting force generated by said pressure differential may be applied to said downstream end of said cartridge.
 9. In a method for transporting a cartridge, having a leading end and a trailing end, through a tube by applying a pneumatic pressure differential to the upstream and downstream portions of said tube relative to the direction of travel and wherein braking of said cartridge is effected by reversing said pressure differential, an improved method of braking said cartridge comprising: communicating the downstream end of said tube with the interior of the trailing end of said cartridge whereby the braking force generated by said reversed pressure differential may act on the upstream end of said cartridge. 